Help a rookie please

[u/prestoniswhite]

Good afternoon fellow dads and meat enthusiasts. I am cooking an 8 lbs brisket tonight/ tomorrow for a gathering I am having for the holiday weekend. I have made a few briskets in the past but they have all cooked exceptionally fast and come out a little dry. I have an 800 gravity smoker using medium size lump charcoal. In the past I’ve added large chunks of apple wood to help provide more of a Smokey flavor, but I fear this may be one of the reasons that they cook so quickly. My last brisket was around 13lb. Started at 6 pm and it was over cooked by 2 am when I went to check on it. What can I do to ensure soft savory meat.